Above the standard offering, at a higher price. Premium is a claim about tier, not about quality.
Latin praemium (a reward, a share taken before the rest), from prae- (before) + emere (to take, buy); a claim about tier and priority, not about quality — the portion set aside ahead of the ordinary share.
Above the standard offering, and priced accordingly. Premium is a claim about tier, and never, by itself, a claim about quality.